gtk: Add GtkSelectionModel

The selection model is a list model interface that takes care of
selections and is to be used by the list model widgets to manage their
selections.

1 files changed, 301 insertions, 0 deletions

diff --git a/gtk/gtkselectionmodel.c b/gtk/gtkselectionmodel.c
new file mode 100644
index 0000000000..0be3961bc2
--- /dev/null
+++ b/gtk/gtkselectionmodel.c
@@ -0,0 +1,301 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#include "config.h"
+
+#include "gtkselectionmodel.h"
+
+#include "gtkintl.h"
+#include "gtkmarshalers.h"
+
+/**
+ * SECTION:gtkselectionmodel
+ * @Title: GtkSelectionModel
+ * @Short_description: An extension of the list model interface that handles selections
+ * @See_also: #GListModel, #GtkSingleSelection
+ *
+ * #GtkSelectionModel is an interface that extends the #GListModel interface by adding
+ * support for selections. This support is then used by widgets using list models to add
+ * the ability to select and unselect various items.
+ *
+ * GTK provides default implementations of the mode common selection modes such as
+ * #GtkSingleSelection, so you will only need to implement this interface if you want
+ * detailed control about how selections should be handled.
+ *
+ * A #GtkSelectionModel supports a single boolean per row indicating if a row is selected
+ * or not. This can be queried via gtk_selection_model_is_selected(). When the selected
+ * state of one or more rows changes, the model will emit the
+ * GtkSelectionModel::selection-changed signal by calling the
+ * gtk_selection_model_selection_changed() function. The positions given in that signal
+ * may have their selection state changed, though that is not a requirement.  
+ * If new items added to the model via the #GListModel::items-changed signal are selected
+ * or not is up to the implementation.
+ *
+ * Additionally, the interface can expose functionality to select and unselect items.
+ * If these functions are implemented, GTK's list widgets will allow users to select and
+ * unselect items. However, #GtkSelectionModels are free to only implement them
+ * partially or not at all. In that case the widgets will not support the unimplemented
+ * operations.
+ *
+ * When selecting or unselecting is supported by a model, the return values of the
+ * selection functions do NOT indicate if selection or unselection happened. They are
+ * only meant to indicate complete failure, like when this mode of selecting is not
+ * supported by the model.
+ * Selections may happen asynchronously, so the only reliable way to find out when an
+ * item was selected is to listen to the signals that indicate selection.
+ */
+
+G_DEFINE_INTERFACE (GtkSelectionModel, gtk_selection_model, G_TYPE_LIST_MODEL)
+
+enum {
+  SELECTION_CHANGED,
+  LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL] = { 0 };
+
+static gboolean
+gtk_selection_model_default_is_selected (GtkSelectionModel *model,
+                                         guint              position)
+{
+  return FALSE;
+}
+
+static gboolean
+gtk_selection_model_default_select_item (GtkSelectionModel *model,
+                                         guint              position,
+                                         gboolean           exclusive)
+{
+  return FALSE;
+}
+static gboolean
+gtk_selection_model_default_unselect_item (GtkSelectionModel *model,
+                                           guint              position)
+{
+  return FALSE;
+}
+
+static gboolean
+gtk_selection_model_default_select_range (GtkSelectionModel *model,
+                                          guint              position,
+                                          guint              n_items,
+                                          gboolean           exclusive)
+{
+  return FALSE;
+}
+
+static gboolean
+gtk_selection_model_default_unselect_range (GtkSelectionModel *model,
+                                            guint              position,
+                                            guint              n_items)
+{
+  return FALSE;
+}
+
+static gboolean
+gtk_selection_model_default_select_all (GtkSelectionModel *model)
+{
+  return gtk_selection_model_select_range (model, 0, g_list_model_get_n_items (G_LIST_MODEL (model)), FALSE);
+}
+
+static gboolean
+gtk_selection_model_default_unselect_all (GtkSelectionModel *model)
+{
+  return gtk_selection_model_unselect_range (model, 0, g_list_model_get_n_items (G_LIST_MODEL (model)));;
+}
+
+static gboolean
+gtk_selection_model_default_query_range (GtkSelectionModel *model,
+                                         guint             *position,
+                                         guint             *n_items)
+{
+  *n_items = 1;
+  return gtk_selection_model_is_selected (model, *position);  
+}
+
+static void
+gtk_selection_model_default_init (GtkSelectionModelInterface *iface)
+{
+  iface->is_selected = gtk_selection_model_default_is_selected; 
+  iface->select_item = gtk_selection_model_default_select_item; 
+  iface->unselect_item = gtk_selection_model_default_unselect_item; 
+  iface->select_range = gtk_selection_model_default_select_range; 
+  iface->unselect_range = gtk_selection_model_default_unselect_range; 
+  iface->select_all = gtk_selection_model_default_select_all; 
+  iface->unselect_all = gtk_selection_model_default_unselect_all; 
+  iface->query_range = gtk_selection_model_default_query_range;
+
+  /**
+   * GtkSelectionModel::selection-changed
+   * @model: a #GtkSelectionModel
+   * @position: The first item that may have changed
+   * @n_items: number of items with changes
+   *
+   * Emitted when the selection state of some of the items in @model changes.
+   *
+   * Note that this signal does not specify the new selection state of the items,
+   * they need to be queried manually.  
+   * It is also not necessary for a model to change the selection state of any of
+   * the items in the selection model, though it would be rather useless to emit
+   * such a signal.
+   */
+  signals[SELECTION_CHANGED] =
+    g_signal_new ("selection-changed",
+                  GTK_TYPE_SELECTION_MODEL,
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL,
+                  _gtk_marshal_VOID__UINT_UINT,
+                  G_TYPE_NONE, 2, G_TYPE_UINT, G_TYPE_UINT);
+  g_signal_set_va_marshaller (signals[SELECTION_CHANGED],
+                              GTK_TYPE_SELECTION_MODEL,
+                              _gtk_marshal_VOID__UINT_UINTv);
+}
+
+/**
+ * gtk_selection_model_is_selected:
+ * @model: a #GtkSelectionModel
+ * @position: the position of the item to query
+ *
+ * Checks if the given item is selected.
+ *
+ * Returns: %TRUE if the item is selected
+ **/
+gboolean
+gtk_selection_model_is_selected (GtkSelectionModel *model,
+                                 guint              position)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->is_selected (model, position);
+}
+
+gboolean
+gtk_selection_model_select_item (GtkSelectionModel *model,
+                                 guint              position,
+                                 gboolean           exclusive)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->select_item (model, position, exclusive);
+}
+
+gboolean
+gtk_selection_model_unselect_item (GtkSelectionModel *model,
+                                   guint              position)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->unselect_item (model, position);
+}
+
+gboolean
+gtk_selection_model_select_range (GtkSelectionModel *model,
+                                  guint              position,
+                                  guint              n_items,
+                                  gboolean           exclusive)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->select_range (model, position, n_items, exclusive);
+}
+
+gboolean
+gtk_selection_model_unselect_range (GtkSelectionModel *model,
+                                    guint              position,
+                                    guint              n_items)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->unselect_range (model, position, n_items);
+}
+
+gboolean
+gtk_selection_model_select_all (GtkSelectionModel *model)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->select_all (model);
+}
+
+gboolean
+gtk_selection_model_unselect_all (GtkSelectionModel *model)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->unselect_all (model);
+}
+
+/**
+ * gtk_selection_model_query_range:
+ * @model: a #GtkSelectionModel
+ * @position: (inout): specifies the position on input, and the first element of the range on output
+ * @n_items: (out): returns the size of the range
+ *
+ * This function allows to query the selection status of multiple elements at once.
+ * It is passed a position and returns a range of elements of uniform selection status.
+ * The returned range is guaranteed to include the passed-in position.
+ * The selection status is returned from this function.
+ *
+ * Returns: %TRUE if the elements in the returned range are selected, %FALSE otherwise
+ */
+gboolean
+gtk_selection_model_query_range (GtkSelectionModel *model,
+                                 guint             *position,
+                                 guint             *n_items)
+{
+  GtkSelectionModelInterface *iface;
+
+  g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), FALSE);
+
+  iface = GTK_SELECTION_MODEL_GET_IFACE (model);
+  return iface->query_range (model, position, n_items);
+}
+
+void
+gtk_selection_model_selection_changed (GtkSelectionModel *model,
+                                       guint              position,
+                                       guint              n_items)
+{
+  g_return_if_fail (GTK_IS_SELECTION_MODEL (model));
+
+  g_signal_emit (model, signals[SELECTION_CHANGED], 0, position, n_items);
+}
+